Chapter 10- The Nervous System: Sensory Systems

dorsal-column-medial lemniscal pathway

an ascending tract that transmits sensory information from touch, pressure, vibration, and proprioceptors to the thalamus

blind spot

anatomically, the optic disk of the retina where there are no photoreceptors; physiologically, the visual field where light strikes the optic disk and, therefore, cannot be detected

refraction

bending of light waves as they travel through media of different densities at an angle other than perpendicular

somatosensory system

branch of the nervous system associated with perception of somatic sensations; associated with receptors in the skin and proprioception

vitreous chamber

cavity of the eye posterior to the lens and ciliary muscle

photoreceptors

cells located in the retina of the eye that detect light waves; include rods and cones

hair cells

cells with stereocilia; receptor cells for hearing and equilibrium

fovea

central point on the retina of the eye, in which visual acuity is greatest

anterior segment

chamber of the eye in front of the lens and ciliary muscle

tastants

chemical substances that give foods their flavors

odorants

chemical substances that must bind to specific chemoreceptors in order to be smelled

lens

clear object in the eye that focuses light on the retina

hyperopia

common visual defect of the eye causing farsightedness

myopia

common visual defect of the eye causing nearsightedness

perception

conscious awareness

transduction

conversion of the energy form of a stimulus into an electrical signal in the form of changes in membrane potential

When a photopigment absorbs light, cGMP levels (increase/decrease).

decrease

external auditory meatus

ear canal

tympanic membrane

eardrum

ampulla

enlargement at the base of each semi-circular canal; contains the hair cells for detecting angular acceleration

A given taste receptor cell responds to only one of the four primary tastes. (true/false)

false

A hair cell in the cochlea can be excited by sounds of different frequencies. (true/false)

false

A single ganglion cell will either by excited or inhibited by light applied to its visual field. (true/false)

false

endolymph

fluid found in the scala media of the cochlea in the inner ear

perilymph

fluid found in the scala vestibuli and scala tympani of the cochlea in the inner ear

aqueous humor

fluid in the anterior cavity of the eye that nourishes the lens and cornea

scala media

fluid-filled duct in the cochlea; also called cochlear duct

scala tympani

fluid-filled duct in the cochlea; also called tympanic duct

scala vestibuli

fluid-filled duct in the cochlea; also called vestibular duct

The pitch of sound vibration reflects its (amplitude/frequency).

frequency

The first neurons that support production of action potentials in the visual pathway are (photoreceptors/bipolar cells/ganglion cells).

ganglion cells

cupula

gelatinous area within the ampulla of the inner ear; contains hair cells that detect angular acceleration

receptor potential

graded potential caused by the opening or closing of ion channels on sensory receptors, and triggered by sensory stimuli

stereocilia

hairlike projections on the upper surface of hair cells in the inner ear that move in response to sound vibrations or acceleration of the head

pupil

hole through which light can enter the eye

acuity

in sensory systems, a measure of the precision of perception

basal cells

in the olfactory system, precursor cells for development of new olfactory receptor cells

modality

in the sensory system, the energy form of a stimulus

circular muscle

inner layer of smooth muscle of the iris; also called constricor muscle

vitreous humor

jelly-like material found in the vitreous chamber of the eye; maintains the spherical structure of the eye

kinocilium

large stereocilia projecting from the receptor cells for equilibrium; the direction of bending in response to acceleration of the body determines the direction of the receptor potentials in receptor cells

Information about touch detected on the left side of the body is transmitted to the brain in the dorsal columns on the ____ side of the spinal cord.

left

The three types of nociceptors are ____, ____, and ____.

mechanical, thermal, polymodal

round window

membrane between the middle and inner ear; dissipates sound waves in the inner ear

oval window

membrane between the middle and inner ear; transmits sound waves from the middle to inner ear

basilar membrane

membrane in the cochlea of the inner ear that separates the scala tympani from the scala media

vestibular membrane

membrane in the cochlea of the inner ear that separates the scala vestibuli and scala media

tectorial membrane

membrane in the organ of Corti in which the tips of stereocilia are embedded

choroid

middle layer of the posterior two-thirds of the eye; contains pigment that absorbs light

vestibulocochlear nerve

nerve that contains the afferents for hearing and equilibrium; cranial nerve VIII

endogenous analgesia systems

neural pathways involved in blocking the transmission of pain signals to the brain, thereby producing analgesia

olfactory receptor cells

neurons that respond to olfactants

emmetropia

normal visual acuity

lateral geniculate body

nucleus of the thalamus that transmits auditory information to the auditory cortex

Rods and cones differ with regard to the type of (retinal/opsin) they contain.

opsin

radial muscle

outer layer of smooth muscle in the iris; also called dilator muscle

optic radiations

pathways from the lateral geniculate body to the visual cortex on either side

cones

photoreceptors that enable visibility during relatively bright light and are responsible for color vision

rods

photoreceptors that enable visibility during relatively low light and are responsible for black-and-white vision

iris

pigmented smooth muscle in the eye that sits in front of the lens and regulates the diameter of the pupil to control the amount of light entering the eye

optic disk

point on the retina where the optic nerve and blood vessels that supply the eye join the retina

auditory cortex

portion of the temporal lobe of the brain that processes auditory information

optic chiasm

portion of the visual neural pathway where some axons from both the right and left optic nerves cross to the opposite side of the brain

lateral inhibition

process during which a stimulus that strongly excites receptors in a certain location inhibits activity in the afferent pathways of other receptors located nearby

olfactory binding protein

protein in the nasal mucus that binds olfactants and transports them to olfactory receptors

A phasic receptor adapts (quickly/slowly) to a constant stimulus.

quickly

rapidly adapting receptors

receptors that decrease in responsiveness to a continuing stimulus; also called phasic receptors

phasic receptors

receptors that decrease in responsiveness to a continuing stimulus; also called rapidly adapting receptors

tonic receptors

receptors that maintain responsiveness to a continuing stimulus; also called slowly adapting receptors

slowly adapting receptors

receptors that maintain responsiveness to a continuing stimulus; also called tonic receptors

accommodation

reflex adjustments of the eye to view near objects; includes rounding of the lens, constriction of the pupil, and posterior movement of the lens

somesthetic sensations

sensations that arise from receptors in the skin

special senses

senses of vision, olfaction, taste, hearing, and equilibrium

nociceptors

sensory receptors on the surface of the body that detect tissue-damaging stimuli; include mechanical nociceptors that respond to intense mechanical stimuli, thermal nociceptors that respond to intense heat, and polymodal nociceptors

mechanoreceptors

sensory receptors that detect physical forces such as pressure or vibration

thermoreceptors

sensory receptors that detect temperature; include peripheral thermoreceptors that detect skin temperature and central thermoreceptors that detect core body temperature

otoliths

small calcium carbonate crystals within the gelatinous material found in the utricles and saccules

ciliary muscles

smooth muscles in the eye attached to the lens by zonular fibers; regulate the curvature of the lens for focusing light

spinothalamic tract

somatosensory pathway that transmits information from thermoreceptors and nociceptors to the thalamus

free nerve endings

somatosensory receptors in the skin that lack identifiable specialized sensory structures; includes some mechanoreceptors, thermoreceptors, and nociceptors

sensory receptors

specialized neuronal structures that detect a specific form of energy in either the internal or external environment

law of specific nerve energies

states that a given sensory receptor is specific for a particular energy form or stimulus type

zonular fibers

strands of connective tissue in the eye that connect the ciliary muscles to the lens and are involved in adjusting the shape of the lens to focus light

utricle

structure of the inner ear; detects forward and backward linear acceleration

saccule

structure of the inner ear; detects up and down acceleration

semicircular canals

structures in the inner ear that contain the receptor cells for rotational accelaration

vestibular apparatus

structures of the inner ear that contain the receptor cells for equilibrium, including the semicircular canals, utricle, and saccule

taste buds

structures on the tongue, roof of the mouth, and pharynx that contain taste receptor cells

receptive field

the area over which an adequate stimulus can produce a response, either excitatory or inhibitory, in an afferent neuron or higher-order neurons

adequate stimulus

the energy form or stimulus type to which a sensory receptor responds best

retina

the innermost layer of the eye; consists of neural tissue and contains photoreceptors

photopigment

the molecule in the photoreceptors that absorbs light, the first step of phototransduction

olfactory nerve

the nerve that contains axons of olfactory receptor cells; cranial nerve I

optic nerve

the nerve that transmits visual information from the eye to the optic chiasm; contains axons of retinal ganglion cells

olfactory epithelium

the organ for smell within the nasal cavity

referred pain

the perception of a painful stimulus as originating at a site on the body distinct from the location of the stimulus

proprioception

the perception of the positions of the limbs and the body

organ of Corti

the sensory organ for sound; located on top of the basilar membrane in the cochlea of the inner ear

The two types of thermoreceptors are ____ and ____.

warm, cold

Rubbing a sore area can decrease the sensation of pain by: a.) activating the endogenous analgesia systems b.) referring the pain to another area of the body c.) activating larger-diameter afferents, which activate an inhibitory interneuron, which inhibits the second-order neurons for pain d.) decreasing the number of action potentials in nociceptor afferents e.) presynaptic inhibition of substance P release

C

The mechanism by which a receptor converts a stimulus into an electrical signal is called: a.) conduction b.) convection c.) transduction d.) modulation e.) propogation

C

The stereocilia for hearing are exposed to: a.) endolymph in the scala vestibuli b.) perilymph in the scala vestibuli c.) endolymph in the scala media d.) perilymph in the scala media e.) endolymph in the scala tympani

C

Which of the following is the correct name of the pathway from the retina to the optic chiasm? a.) optic tract b.) optic radiations c.) optic nerve d.) optic disk

C

The strength of a stimulus is coded by: a.) the size of the receptor potential b.) the size of the action potentials c.) the frequency of action potentials d.) both a and c e.) all of the above

D

In the dorsal column-medial lemniscal pathway, a.) proprioception information is transmitted to the brain b.) the first-order neuron communicates to the second-order neuron in the dorsal horn of the spinal cord c.) the pathway crosses to the contralateral side in the spinal cord d.) both a and c e.) all of the above

A

Where would you expect to find the ascending tracts for somatosensory information? a.) in the white matter of the spinal cord b.) in a spinal nerve c.) in the gray matter of the spinal cord d.) none of the above

A

Which of the following observations best illustrates the concept of the labeled line? a.) when a boxer gets punched in the eye, he perceives light b.) rotation of the head stimulates certain receptors in the vestibular system but not those in the visual system c.) information from different photoreceptors converges on a single ganglion cell that projects to the lateral geniculate nucleus d.) hair cells in the cochlea are stimulated by sound vibrations over a wide range of frequencies

A

The ability to perceive different frequencies in sound vibrations is based on the fact that: a.) the stereocilia of any given hair cell respond to only one frequency b.) different areas of the basilar membrane resonate at different frequencies, such that sound of a particular frequency causes only a certain region of the membrane to vibrate c.) the frequency of action potentials in the cochlear nerve varies in proportion to the frequency of a sound stimulus

B

The parasympathetic nervous system causes: a.) contraction of the radial muscle of the iris b.) contraction of the ciliary muscle c.) pupillary dilation d.) both a and c e.) all of the above

B

Which of the following best illustrates the concept of an adequate stimulus? a.) when a boxer gets punched in the eye, he perceives light b.) rotation of the head stimulates certain receptors in the vestibular system but not those in the visual system c.) information from different photoreceptors converges on a single ganglion cell that projects to the lateral geniculate nucleus d.) hair cells in the cochlea are stimulated by sound vibrations over a wide range of frequencies

B

Which of the following is the correct name of the pathway from the lateral geniculate nucleus of the thalamus to the visual cortex? a.) optic tract b.) optic radiations c.) optic nerve d.) optic chiasm e.) optic disk

B

In lateral inhibition, a.) the nervous system produces contrast to emphasize more-important information over less-important b.) afferent neurons with neighboring receptive fields inhibit each other's communication to second-order neurons c.) the ability to locate the site of a stimulus is enhanced d.) both a and c e.) all of the above

E

eustachian tube

a canal that connects the middle ear with the pharynx and allows equilibration of air pressure across the eardrum

generator potential

a change in membrane potential; also known as receptor potential

macula lutea

a depression in the center of the retina that contains the fovea; contains a high density of cones

slow pain

a poorly localized, dull, aching sensation produced by activation of nociceptors; transmitted by C fibers

fast pain

a sharp, pricking sensation that can be easily localized and is produced by activation of nociceptors; transmitted by A-delta fibers

sensory unit

a single afferent neuron and all sensory receptors associated with it

cochlea

a spiral-shaped structure in the inner ear that contains the receptor cells for hearing

analgesia

absence of pain perception

The process by which the lens becomes stronger for close-up vision is called ____.

accommodation

Receptors are most sensitive to energy from the ____ stimulus.

adequate

cold receptors

thermoreceptors that increase in responsiveness as the temperature decreases

warm receptors

thermoreceptors that increase responsiveness with an increase in temperature

ossicles

three bones in the middle ear that transmit sound vibrations from the eardrum to the cochlea; include the malleus, incus, and stapes

sclera

tough connective tissue that makes up the white of the eye

optic tract

tract containing axons of retinal ganglion cells that transmit visual information from the optic chiasm to the lateral geniculate nucleus of the thalamus

cornea

transparent structure at the front of the eye that allows light waves to enter

Odorant molecules must be dissolved in mucus if they are to bind to olfactory receptors. (true/false)

true

The visual cortex on the left side of the brain receives information from the right eye only. (true/false)

true